It was the latest in a series of fatal crashes that has plagued the industry for decades.
The helicopter was carrying one pilot and four passengers when it crashed on Thursday afternoon just off Kalalau Beach, the Kauai Fire Department said.
The beach is on the Na Pali Coast on Kauai's North Shore, an area that is otherwise reachable only by hiking or boat. The area's geography of tall seaside cliffs and sharp mountain ridges can contribute to turbulent air and quick weather changes that pose hazards for aviation.
Kauai Police Chief Rudy Tai said two of the people who died were a man and woman from Massachusetts. Notification of next of kin is pending for the third, he said. He declined to provide details on survivors' conditions.
At least 16 people have died in helicopter crashes in Hawaii in the past seven years, including two crashes in 2019. A skydiving plane crash in Hawaii that year killed 11 people. Investigators blamed the pilot's aggressive takeoff.
In 2023, the Federal Aviation Administration set up a new process for air tour operators in Hawaii wanting to fly at lower altitudes, including recommendations for pilot training and qualifications, as well as aircraft equipment.
The agency said it would thoroughly review each operator's safety plan before issuing an authorisation.
The helicopter was operated by Airborne Aviation, which does sightseeing tours of Kauai's canyons, shoreline and waterfalls. Airborne advertises a "doors-off thrill seekers adventure tour" that seats up to four people.
There have been no tours since the crash, the company said on Friday.
Airborne Aviation said it was co-operating with investigators.
"Our hearts are with the families and loved ones affected by this devastating event, and we extend our deepest condolences during this incredibly difficult time," the company said in a statement.
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